No-Insulation BSCCO Coils Impregnated With Low-Melting Point Metal

This paper presents the experimental results of the (Bi,Pb)
₂
Sr
₂
Ca
₂
Cu
₃
O
₁₀
(BSCCO) coils impregnated with low-melting point metal, whose melting point is 60 °C. The coils were layer-wound without turn-to-turn insulation, i.e., no-insulation (NI). We fabricated the coils with polycarbonate bobbin and casing and the coils with aluminum alloy bobbins and casing. The coils with polycarbonate bobbin and casings showed severe degradation after impregnation. The coils with aluminum alloy ones showed less degradation. A long decay time of the magnetic field during a sudden discharge was measured. The decay time was shortened to be 1/39 by an inter-layer insulation with polyimide sheet. Partial insulation, i.e., electrical insulation between adjacent layers, was effective in reducing this long time constant, even for a BSCCO NI coil.